EP3578536B1

EP3578536B1 - Method for producing fluorohalogenated hydrocarbon

Info

Publication number: EP3578536B1
Application number: EP18748736.8A
Authority: EP
Inventors: Kazuhiro Takahashi; Tatsuya TAKAKUWA
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2017-01-31
Filing date: 2018-01-31
Publication date: 2023-12-06
Anticipated expiration: 2038-01-31
Also published as: EP4293005A3; US11034634B2; EP3578536A1; JP2018123126A; CN110248918A; JP6319535B1; EP4293005A2; US20210130267A1; CN110248918B; WO2018143271A1; EP3578536A4

Description

Technical Field

The present invention provides a method for producing at least one fluorine-containing halogenated hydrocarbon selected from 1,1,1,2,2-pentafluoropropane (HFC-245cb), 1,1,1,3,3-pentafluoropropane (HFC-245fa), E,Z-1,3,3,3-tetrafluoropropene (E,Z-HFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), and 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), the method being a production method for stably obtaining a target compound. Fluorine-containing halogenated hydrocarbons obtained in the present invention include fluorinated hydrocarbons that contain fluorine as a halogen as well as fluorine-containing halogenated hydrocarbons that contain other halogens in addition to fluorine.

Background Art

Fluorine-containing halogenated hydrocarbons, such as HFC-245cb, HFC-245fa, E,Z-HFO-1234ze, HFO-1234yf, HCFO-1233xf, and HCFO-1233zd have been conventionally used in various applications, such as a heat medium (refrigerant), foaming agent, solvent, detergent, propellant, and fire extinguisher. It is known that such fluorine-containing halogenated hydrocarbons are produced by reacting a chlorine-containing compound and hydrogen fluoride (HF) in the presence of a catalyst in a vapor phase. Specifically, as a method for producing HFO-1234yf, which is considered to be promising as a refrigerant for car air conditioners because of its low global warming potential (GWP), the following various methods are disclosed.
For example, WO 2013/141409 and WO 2013/111911 disclose a method for producing 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and HFO-1234yf by vapor-phase fluorination reaction using 1,1,1,2,3-pentachloropropane (HCC-240db) as a starting material, and anhydrous HF and a catalyst. WO 2007/079431 discloses a method for producing HFO-1234yf by vapor-phase fluorination reaction using 1,1,2,3-tetrachloropropene (HCO-1230xa) as a starting material, and anhydrous HF and a catalyst.
Vapor-phase fluorination reaction using a catalyst has a problem of catalyst deactivation caused by repeated reaction. Such a catalyst deactivation problem is significant when a starting material having a double bond, such as HCFO-1233xf, is used because it is likely to become a catalyst poison. Accordingly, WO 2013/114015 , for example, discloses adding oxygen or chlorine to a fluorination reactor to inhibit catalyst deactivation.
US-A-2015/0080619 discloses a method for producing 2,3,3,3-tetrafluoropropene (1234yf), comprising reactively fluorinating a halopropane and/or halopropene to 1234yf using HF; recovering a gaseous stream obtained from the reaction; cooling and partially condensing the gaseous stream obtained from the reaction, to give a partially condensed stream; separating the partially condensed stream into a gaseous fraction and a liquid fraction; compressing the gaseous fraction to give a compressed gaseous fraction; compressing the liquid fraction to give a compressed liquid fraction; distilling the compressed gaseous fraction and the compressed liquid fraction to give a 1234yf stream, a HCl stream, and a stream of unreacted HF.
Catalyst deactivation is apparently affected by the concentration of a starting material (starting material organic matter). To reduce the concentration of the starting material to inhibit catalyst deactivation, a method for increasing the excess percentage of HF or a method for reducing the reaction pressure in fluorination reaction is known. Reduction in reaction pressure reduces the condensation temperature in the condenser of a distillation column used for removing a side product such as hydrogen chloride (HCl), which increases equipment cost and other costs.

Summary of Invention

Technical Problem

To solve the above problem, one option is a method for compressing gas at the outlet of a fluorination reactor using a compressor to increase the condensation temperature in a condenser. However, a HF-containing gas may reduce its temperature and condense by compression. This is because when HF is in a stable state, 6 molecules are associated, and HF is likely to condense by heat absorbed during compression. Condensation not only makes compression difficult but also may break the compressor in the worst case.
The present invention solves these problems, and aims to provide a method for producing a fluorine-containing halogenated hydrocarbon, comprising the step of compressing gas at the outlet of a fluorination reactor using a compressor, wherein the method is for stably obtaining a target compound by preventing HF contained in the outlet gas from condensing during compression.

Solution to Problem

As a result of extensive research to achieve the above object, the present inventors found that the object can be attained by a method for producing a fluorine-containing halogenated hydrocarbon comprising a specific separation step of separating a reaction product (gas at the outlet of a fluorination reactor) containing HF, HCl, and organic matter containing a fluorine-containing halogenated hydrocarbon into multiple components. The present invention was thus accomplished.
Specifically, the present invention relates to a method (the "present method" hereinafter) for producing at least one fluorine-containing halogenated hydrocarbon selected from 1,1,1,2,2-pentafluoropropane (HFC-245cb), 1,1,1,3,3-pentafluoropropane (HFC-245fa), E,Z-1,3,3,3-tetrafluoropropene (E,Z-HFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), comprising

a step of reacting a chlorine-containing compound and HF in a vapor phase, and
a step of separating a reaction product containing HF, HCl and organic matter containing the fluorine-containing halogenated hydrocarbon into multiple components, comprising the steps of
1. (1) separating the reaction product into a gas phase and a liquid phase,
2. (2) increasing the pressure of the liquid phase and supplying the liquid phase into a distillation column A,
3. (3) compressing the gas phase in series in two or more stages using a compressor and heating it by a heater to maintain a fraction of compressed gas of 1 at each stage, and supplying the gas phase into distillation column A, and (4) separating a first stream containing the HCl from the top of distillation column A, and separating a second stream containing the organic matter and the HF from the bottom of distillation column A.

Preferred embodiments of the invention are as defined in the appended dependent claims and/or in the following detailed description.

Advantageous Effects of Invention

According to the present method, in an embodiment in which reaction pressure in a fluorination reaction is reduced to inhibit catalyst deactivation, and gas at the outlet of a fluorination reactor is compressed using a compressor, condensation of HF contained in the gas at the reactor outlet can be prevented, thus leading to the subsequent distillation step. Accordingly, a fluorine-containing halogenated hydrocarbon, which is a target compound, can be stably obtained without breaking the compressor.

Brief Description of Drawings

Fig. 1 is a flow chart showing an example of the step of separating a reaction product into multiple components in the present method.
Fig. 2 is a flow chart showing an example of the step of separating a reaction product into multiple components in a conventional method for producing a fluorine-containing halogenated hydrocarbon.

Description of Embodiments

The present method is a method for producing at least one fluorine-containing halogenated hydrocarbon selected from 1,1,1,2,2-pentafluoropropane (HFC-245cb), 1,1,1,3,3-pentafluoropropane (HFC-245fa), E,Z-1,3,3,3-tetrafluoropropene (E,Z-HFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), comprising

a step of reacting a chlorine-containing compound and HF in a vapor phase, and
a step of separating a reaction product containing HF, HCl and organic matter containing the fluorine-containing halogenated hydrocarbon into multiple components, comprising the steps of
1. (1) separating the reaction product into a gas phase and a liquid phase,
2. (2) increasing the pressure of the liquid phase and supplying the liquid phase into a distillation column A,
3. (3) compressing the gas phase in series in two or more stages using a compressor and heating it by a heater to maintain a fraction of compressed gas of 1 at each stage, and supplying the gas phase into distillation column A, and
4. (4) separating a first stream containing the HCl from the top of distillation column A, and separating a second stream containing the organic matter and the HF from the bottom of distillation column A.

In the method having the above features of the invention, in the step of separating a reaction product containing HF, HCl, and organic matter containing a fluorine-containing halogenated hydrocarbon into multiple components, the gas phase is compressed in series in two or more stages using a compressor, and heated by a heater to maintain a fraction of compressed gas of 1 at each stage.
According to the present method, in an embodiment in which the reaction pressure in a fluorination reaction is reduced to inhibit catalyst deactivation, and gas at the outlet of a fluorination reactor is compressed using a compressor, condensation of HF contained in the gas at the reactor outlet can be prevented, thus leading to the subsequent distillation step. Accordingly, a fluorine-containing halogenated hydrocarbon, which is a target compound, can be stably obtained without breaking the compressor.
Hereinbelow, the present method is explained by each step with reference to Fig. 1.

Step 1 (Gas-liquid separation step of reaction product)

Of the steps of separating the reaction product containing HCl, HF, and organic matter containing a fluorine-containing halogenated hydrocarbon into multiple components, step (1) is the step of separating the reaction product into a gas phase and a liquid phase.
When the chlorine-containing compound and the HF are reacted in a vapor phase in one stage, the reaction product means a reaction product containing a fluorine-containing halogenated hydrocarbon obtained by the one-stage reaction. When the chlorine-containing compound and the HF are reacted in a vapor phase in multiple stages, the reaction product means a reaction product containing a fluorine-containing halogenated hydrocarbon obtained by the reaction in the final stage.
The present method can be applied for the method for producing a fluorine-containing halogenated hydrocarbon comprising the step of reacting a chlorine-containing compound and HF in a vapor phase. Such a method is generally performed using a fluorination catalyst, and at least one of chlorine-containing alkanes or chlorine-containing alkenes as a chlorine-containing compound.
Preferable examples of chlorine-containing compounds include at least one selected from 1,1,1,2,3-pentachloropropane (HCC-240db), 1,1,2,2,3-pentachloropropane (HCC-240aa), 1,1,2,3-tetrachloropropene (HCO-1230xa), 2,3,3,3-tetrachloropropene (HCO-1230xf), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), 2,3-dichloro-3,3-difluoropropene (HCFO-1232xf), 1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc), 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), 2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db), 3,3-dichloro-1,1,1-trifluoropropane (HCFC-243fa), 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), and 3-chloro-1,1,1,3-tetrafluoropropane (HCFC-244fa). Such chlorine-containing compounds can be used in accordance with the kind of a target compound or the number of reaction stages (one-stage reaction or two or more multiple-stage reaction) . Two or more kinds of chlorine-containing compounds can be mixed as necessary for use.
When the target compound is HFO-1234yf, HCFO-1233xf is used as a starting material and is subjected to one-stage vapor-phase fluorination reaction to thereby obtain a reaction product containing HFO-1234yf. When starting materials (chlorine-containing compounds) other than HCFO-1233xf are used, one-stage vapor-phase fluorination reaction may be performed to obtain a reaction product containing HFO-1234yf; however, to increase the yield of target product HFO-1234yf, the starting material may be subjected to multiple-stage vapor-phase fluorination reaction to thereby obtain a reaction product containing HFO-1234yf. When the starting material is subjected to multiple-stage (e.g., two-stage) vapor-phase fluorination reaction, the starting material chlorine-containing compound is subjected to vapor-phase fluorination using HF in the presence of a fluorination catalyst to thereby obtain an intermediate product containing HCFO-1233xf, and then the intermediate product containing HCFO-1233xf is further subjected to vapor-phase fluorination using HF in the presence of a fluorination catalyst, thus obtaining a reaction product containing HFO-1234yf by two-stage reaction.
When the target compound is HFO-1234yf, preferable examples of the chlorine-containing compound include at least one selected from 1,1,1,2,3-pentachloropropane (HCC-240db), 1,1,2,2,3-pentachloropropane (HCC-240aa), 1,1,2,3-tetrachloropropene (HCO-1230xa), 2,3,3,3-tetrachloropropene (HCO-1230xf), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), 2,3-dichloro-3,3-difluoropropene (HCFO-1232xf), 1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc), 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), and 2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db). Of these, preferable starting materials are those containing HCFO-1233xf because a reaction product containing target compound HFO-1234yf can be obtained by one-stage vapor-phase fluorination reaction.
Hereinbelow, by representing an example in which HFO-1234yf is the target compound, two-stage reaction including the first reaction step and the second reaction step is explained. When HCFO-1233xf is used as a starting material, the vapor-phase fluorination reaction in the second reaction step is mainly used to obtain a HFO-1234yf-containing reaction product in one stage.

(i) First reaction step

In the first reaction step, in the presence of a fluorination catalyst, the aforementioned starting material (chlorine-containing compound: sometimes referred to as a starting material compound) and HF are reacted under heating in a vapor phase.
In the first reaction step, the reaction of the starting material compound with HF under the above conditions yields a product containing HCFO-1233xf that is an intermediate for HFO-1234yf.
The first reaction step requires the reaction of the starting material compound with HF in a vapor phase in the presence of a fluorination catalyst. As long as the starting material compound and HF come into contact with each other in a gas form within the reaction temperature range described below, the starting material compound may be in a liquid form when supplied. For example, when the starting material compound is liquid at an ordinary temperature and ordinary pressure, it is vaporized using a vaporizer (vaporization region), passed through a preheating region, and then supplied to a mixing region wherein the starting material compound comes into contact with HF, thereby the reaction can be conducted in a vapor phase. The reaction may also be carried out by supplying the starting material compound in a liquid phase to a reactor, and vaporizing the compound when the compound attains the reaction range with HF. The reaction may also be carried out by superheating vaporized HF, supplying the starting material thereto to vaporize the starting material, and supplying the mixture to a reactor.
As a fluorination catalyst used in the first reaction step, a known catalyst that shows activity in fluorination reaction with HF can be used. Usable examples include metal oxides and fluorinated metal oxides, such as chromium oxide, fluorinated chromium oxide, aluminum fluoride, and fluorinated aluminum oxide. In addition, metal fluorides, such as MgF₂, TaF₅, and SbF₅ can also be used.
Of these catalysts, although there is no limitation, a chromium oxide of the composition formula CrO_m wherein 1.5<m<3 is preferable, and m is more preferably 2<m<2.75 and still more preferably 2<m<2.3. The chromium oxide catalyst can be of any shape, for example, powder or pellets, as long as it suits the reaction. In particular, pellets are preferable. Such chromium oxide catalysts can be prepared by a method described in JP-A-1993-146680 .
Fluorinated chromium oxide can be prepared by a method described in JP-A-1993-146680 . For example, fluorinated chromium oxide can be prepared by fluorinating the chromium oxide obtained by the above-described method with HF (HF treatment).
The degree of fluorination is not limited. For example, a fluorinated chromium oxide having a fluorine content of 10-45 wt.% may be suitably used.
Further, a chromium-based catalyst disclosed in JP-A-1999-171806 A also may be used as a chromium oxide catalyst or fluorinated chromium oxide catalyst. The chromium-based catalyst is in an amorphous state and comprises, as a main component, a chromium compound containing at least one metallic element selected from indium, gallium, cobalt, nickel, zinc, and aluminum. The chromium in the chromium compound has an average valence number of +3.5 to +5.0.
The above-described fluorination catalyst may be used as supported on a carrier such as alumina and activated carbon. There is no limitation to the methods for vaporizing the starting material compound in the reaction range. The starting material compound may be vaporized into a vapor phase by, for example, filling a preheating region with a material that exhibits excellent thermal conductivity, exerts no catalytic activity in the reaction of the present invention, and is stable to HF, such as metal pieces of corrosion-resistant materials including nickel beads, alumina beads, Hastelloy, Inconel, Monel, Incolloy, and the like, so as to heat the preheating region to not less than the vaporization temperature of the starting material compound; and supplying the starting material compound in a liquid phase thereinto.
HF may generally be supplied to a reactor in the form of a vapor phase together with the starting material compound. The amount of HF to be supplied is generally 1-100 moles, preferably 5-50 moles, and more preferably 10-30 moles, per mole of the starting material compound. By setting the amount within such a range, the conversion of the starting material compound and the selectivity of components, such as HCFO-1233xf, that can be intermediates for 2,3,3,3-tetrafluoropropene (HFO-1234yf), can be maintained within an excellent range.
The starting material may be supplied to the reactor as is or may be diluted with an inert gas such as nitrogen, helium, or argon, and then supplied to the reactor.
The form of the reactor used in the first reaction step is not limited. Examples of usable reactors include an adiabatic reactor packed with a catalyst. Also usable is e.g. a multitubular reactor in which a heating medium is used to cool the reactor and to homogenize the temperature distribution within the reactor.
The reactor is preferably made of an alloy containing 30% or more by weight of nickel. More specifically, a reactor formed of a material that is resistant to the corrosive action of HF, such as Hastelloy, Inconel, Monel, and Incolloy, is preferably used.
In the first reaction step, the reaction temperature, i.e., the temperature in the reactor, is 200-500°C, preferably 250-400°C, and more preferably 300-350°C. If the reaction temperature is higher than this range, the selectivity of components, such as HCFO-1233xf, that can be intermediates for HFO-1234yf undesirably decreases. If the reaction temperature is lower than this range, the conversion of the starting material compound undesirably decreases.
The pressure during the reaction is not limited, as long as the starting material compound and HF can be present in a vapor phase, and the reaction may be conducted under ordinary pressure or increased pressure. More specifically, the first reaction step may be conducted under atmospheric pressure (0.1 MPa). This step also may be conducted under increased pressure and temperature condition at which the starting material does not turn into a liquid phase.
The reaction time is not limited. The residence time, which is represented by W/Fo, may be generally adjusted to a range of 1-10 (g · sec/cc). W/Fo is the ratio of the catalyst weight W (g) in a vapor phase to the total flow rate Fo (flow rate at 0°C, 0.1 MPa: cc/sec) of the starting material gases (starting material compound, HF, and inert gas) supplied to the reaction system.
Under the above reaction conditions, a reaction product containing HCFO-1233xf can be obtained at the reactor outlet.

(ii) Second reaction step

In the second reaction step, the product obtained in the first reaction step is used as a starting material and reacted with HF in a vapor phase in the presence of a fluorination catalyst under heating.
The product obtained in the first reaction step contains HCFO-1233xf as a main component and may also contain a chloropropane compound, such as 1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc) and 2,3-dichloro-3,3-difluoropropane (HCFO-1232xf), or a chloropropene compound. When the product containing e.g. a chloropropane compound or a chloropropene compound is used as is as a starting material and reacted with HF in the presence of a fluorination catalyst in the second reaction step, not only HCFO-1233xf but also the components contained in the product, such as HCFC-242dc and HCFO-1232xf, can be converted to HFO-1234yf. As a result, the desired HFO-1234yf can be obtained with high selectivity.
As a fluorination catalyst used in the second reaction step, the same catalyst as disclosed and exemplified above for the first reaction step can be used.
HF used as a starting material may be generally supplied to a reactor in the form of vapor phase together with the reaction product obtained in the first reaction step. The amount of HF supplied in the second reaction step is generally 1-50 moles, preferably 5-30 moles, and more preferably 7-20 moles, per mole of the reaction product obtained in the first reaction step. The amount of HF supplied in the second reaction step is preferably within the above-described range and smaller than the amount of HF actually supplied in the first reaction step.
When the amount of HF contained in the reaction product obtained in the first reaction step is within the aforementioned range, a fluorination reaction in the second reaction step can be conducted by using only the reaction product obtained in the first reaction step, without adding further HF. When the amount of HF contained in the reaction product obtained in the first reaction step is larger than the aforementioned range, the reaction product may be used as a starting material in the second reaction step after reducing the amount of HF contained therein by a method such as distillation.
The selectivity of HFO-1234yf can be maintained in a desirable range by using anhydrous HF within the above-described range in the presence of a fluorination catalyst.
To maintain catalyst activity for a long period of time, oxygen may be supplied to the reactor as entrained with the aforementioned starting material, especially in the second reaction step. In this case, the amount of oxygen to be supplied may be 0.01-0.3 mole per mole of the reaction product obtained in the first reaction step.
The form of the reactor used in the second reaction step is not limited. Examples of usable reactors include an adiabatic reactor packed with a catalyst and a multitubular reactor in which a heating medium is used to cool the reactor. As in the first reaction step, a reactor formed of a material that is resistant to the corrosive action of HF, such as Hastelloy, Inconel, and Monel, is preferably used.
In the second reaction step, the reaction temperature, i.e., the temperature in the reactor, is 200-500°C, preferably 300-450°C, and more preferably 350-400°C. If the reaction temperature is higher than this range, the selectivity of HFO-1234yf undesirably decreases. If the reaction temperature is lower than this range, the conversion of the starting material compound undesirably decreases. In particular, the reaction temperature in the second reaction step is preferably within the above-described range and lower than that in the first reaction step.
The pressure during the reaction is not limited, and the reaction may be conducted under ordinary pressure or increased pressure. More specifically, the reaction in the present invention may be conducted under atmospheric pressure (0.1 MPa), and may be also conducted under an increased pressure up to 0.5 MPa.
The reaction time is not particularly limited. However, the contact time, which is represented by W/Fo, may be generally adjusted to 5-20 g • sec/cc. W/Fo is the ratio of the amount of packed catalyst W(g) to the total flow rate of the starting material gases supplied to the reactor in the second reaction step (total amount of product obtained in the first reaction step and HF) Fo (flow rate at 0°C, 1 atm (0.1 MPa): cc/sec).

(iii) Reaction product

According to the aforementioned process comprising the two-stage reaction step, the reaction product that contains the desired HFO-1234yf can be obtained with high selectivity at the reactor outlet in the second reaction step.
The reaction product contains unreacted HF and HCl, and organic matter containing HFO-1234yf. Although the kind of organic matter containing HFO-1234yf depends on the kind of starting material, examples of organic matter other than HFO-1234yf include HCFO-1233xf, 1,1,1,2,2-pentafluoropropane (HFC-245cb), HCFO-1233zd and 1,3,3,3-tetrafluoropropene (HFO-1234ze).
In step (1), the reaction product (S11 in Fig. 1) containing a fluorine-containing halogenated hydrocarbon (HFO-1234yf in the above examples) is separated into a gas phase (S12) and a liquid phase (S16). A known gas liquid separator can be used for separating the reaction product into a gas phase and a liquid phase. From the viewpoint of efficient separation, a cooler (condenser) is preferably used. By the gas liquid separation, most of the HF is separated into a liquid phase, a small amount of the HF is separated into a gas phase, and substantially all of the HCl is separated into a gas phase.

Step (2) (Step of increasing the pressure of the liquid phase and supplying the liquid phase to the distillation column A)

In step (2), the pressure of the liquid phase separated in step 1 is increased, and the liquid phase is supplied to the distillation column A.
A pump can be used for increasing the pressure of the liquid phase. It is necessary to set pressure increase conditions so that the pump discharge pressure is higher than the operating pressure of the distillation column A, and the pressure is preferably 5-10% higher than the operating pressure of the distillation column.

Step (3) (Step of compressing the gas phase and supplying the gas phase to the distillation column A)

Step (3) is the step of supplying the gas phase separated in step 1 to the distillation column A. Specifically, the gas phase is compressed in series in two or more stages using a compressor, and the gas phase is heated by a heater to thereby maintain the fraction of gas after compression at 1 in each stage. The gas fraction is represented by the amount of gas phase/(amount of liquid phase + amount of gas phase) based on a mole.
While the gas phase is compressed in series in two or more stages and is supplied to the distillation column A, as long as the fraction of gas after compression can be maintained at 1 in each stage, the number and location of heaters are not limited. The temperature of the heater is not limited as long as the fraction of gas after compression can be maintained at 1 in each stage, and it is preferably 0-150°C. In this temperature range, when n compressors are disposed in series for performing n stage compression, it is preferable to dispose n-1 heaters between stages. In the present method, it is preferable to maintain the fraction of gas obtained from the first stage compression at 1 until the gas reaches the distillation column A through the multiple stages.
In Fig. 1, as a compressor for compressing the gas phase, two compressors, i.e., a first stage compressor and a second stage compressor are provided, and a heater is disposed between the first and second stage compressors. By performing compression at each stage under heating with a heater, the fraction of compressed gas is maintained at 1 at each stage. The temperature of the heater is not limited; however, when one heater is disposed between the first and second stage compressors as described above, the temperature of the heater is preferably ≤ 100°C, and more preferably 30-80°C.
In the present invention, when the gas phase is compressed in series in two or more stages, the gas phase in each stage is compressed by a factor of ≥ 2. For example, when compression is performed in two stages, the gas phase in each stage is preferably compressed by a factor of 2-5.

Step (4) (Step of performing distillation in distillation column A)

In step (4), the first stream (S18) containing HCl is separated from the top of the distillation column A, and the second stream (S19) containing the organic matter and HF is separated from the bottom of the distillation column A.
Distillation in the distillation column A is performed according to a known method. The operating pressure of the distillation column can be selected between 0.1-2 MPa. Since the condensation temperature becomes higher as the pressure increases, cooling cost can be reduced; however, considering the cost increase due to increased device thickness or leakage risk resulting from increased pressure, a suitable pressure is selected.
The second stream separated from the bottom of the distillation column A usually contains HF and organic matter containing a side product, unreacted starting material, or target fluorine-containing halogenated hydrocarbon.

Step (5) (Step of performing distillation in distillation column B)

The present method may further comprise the step of supplying the second stream to the distillation column B, and separating the second stream by distillation into the third stream (e.g., S20) containing the fluorine-containing halogenated hydrocarbon and the fourth stream (e.g., S21) containing HF and organic matter other than the fluorine-containing halogenated hydrocarbon. In this step, the second stream containing target organic matter is subjected to fractional distillation to separate the target compound. Distillation conditions can be suitably determined in accordance with e.g. the kind of the target compound and difference in boiling point. As the distillation column B, those capable of performing multistage distillation can be used as necessary. In this case, distillation conditions can be determined in a manner such that the target compound can be more finely separated.
Distillation in the distillation column B can be performed according to a known method. The operating pressure of the distillation column can be selected between 0.1-2 MPa, as in the distillation column A. Operating the distillation column A at a pressure higher than that of the distillation column B will eliminate the need for compression between the distillation columns, and thus, is convenient.
The third stream containing the fluorine-containing halogenated hydrocarbon includes a composition mainly containing the target fluorine-containing halogenated hydrocarbon. The fluorine-containing halogenated hydrocarbon can be further subjected to a crude purification step and a fine purification step to yield a final product. Specific methods for the crude purification step and the fine purification step are not limited. For example, water washing, dehydration (drying), additional distillation, liquid-liquid separation, or other means can be applied to these steps.
The fourth stream containing HF and organic matter other than the fluorine-containing halogenated hydrocarbon generally contains HF and organic matter other than the target compound of fluorine-containing halogenated hydrocarbon. After the components contained in the fourth stream have suitably undergone a crude purification step, they can be recycled for vapor-phase fluorination reaction of the chlorine-containing compound and HF in the present invention.
In the present method, steps (1)-(5) can be performed in this order; however, steps (2) and (3) can be performed in random order or at the same time.

Examples

The present invention is detailed below with reference to Examples and Comparative Examples. Examples and Comparative Examples are based on simulation.

Example 1

The flow rate (mol/h) of each stream (S11-S21) obtained in the separation of gas at the outlet of a fluorination reactor into multiple components as shown in Fig. 1 was examined. Table 1 shows the flow rate. Example 1 is a method for producing HFO-1234yf as a target compound.

Table 1

Mole flow Kmol/hr	S11	S12	S13	S14	S15	S16	S17	S18	S19	S20	S21
HF	1.85	0.059	0.059	0.059	0.059	1.79	1.79	0.000	1.85	0.025	1.82
HCL	0.028	0.028	0.028	0.028	0.028	0.000	0.000	0.028	0.000	0.000	0.000
1233XF	0.066	0.010	0.010	0.010	0.010	0.056	0.056	0.000	0.066	0.000	0.066
1234YF	0.028	0.018	0.018	0.018	0.018	0.010	0.010	0.000	0.028	0.028	0.000
245CB	0.012	0.008	0.008	0.008	0.008	0.004	0.004	0.000	0.012	0.011	0.000
1233ZD	0.002	0.000	0.000	0.000	0.000	0.002	0.002	0.000	0.002	0.000	0.002
E1234ZE	0.004	0.003	0.003	0.003	0.003	0.001	0.001	0.000	0.004	0.004	0.000
Other	0.013	0.009	0.009	0.009	0.009	0.004	0.004	0.009	0.004	0.000	0.003
Temperature (°C)	146	-20	10.8	35	72.0	-1.5	-1.0	-37.8	61.9	42.6	81.6
Pressure (MPaG)	0.02	0.005	0.23	0.23	0.95	0.005	0.95	0.9	0.95	0.86	0.91
Vapor fraction	1	1	1	1	1	0	0	1	0	1	0

Vapor fraction : Amount of gas phase / (\begin{array}{l} amount liquid phase + \\ amount of gas phase \end{array}) based on mole

Comparative Example 1

The flow rate (mol/h) of each stream (S31 to S40) obtained in the separation of gas at the outlet of a fluorination reactor into multiple components as shown in Fig. 2 was examined. The same conditions as in Fig. 1 were used except that the heater was not disposed between the first stage and the second stage compression using a compressor. Table 2 shows the flow rate. Comparative Example 1 is a method for producing HFO-1234yf as a target compound.

Table 2

Mole flow Kmol/hr	S31	S32	S33	S34	S35	S36	S37	S38	S39	S40
HF	1.85	0.059	0.059	0.059	1.79	1.79	0.000	1.85	0.025	1.82
HCL	0.028	0.028	0.028	0.028	0.000	0.000	0.028	0.000	0.000	0.000
1233XF	0.066	0.010	0.010	0.010	0.056	0.056	0.000	0.066	0.000	0.066
1234YF	0.028	0.018	0.018	0.018	0.010	0.010	0.000	0.028	0.028	0.000
245CB	0.012	0.008	0.008	0.008	0.004	0.004	0.000	0.012	0.011	0.000
1233ZD	0.002	0.000	0.000	0.000	0.002	0.002	0.000	0.002	0.000	0.002
E1234ZE	0.004	0.003	0.003	0.003	0.001	0.001	0.000	0.004	0.004	0.000
Other	0.013	0.009	0.009	0.009	0.004	0.004	0.009	0.004	0.000	0.003
Temperature (°C)	146	-20	10.8	47.2	-1.5	-1.0	-37.8	61.9	42.6	81.6
Pressure (MPaG)	0.02	0.005	0.23	0.95	0.005	0.95	0.9	0.95	0.86	0.91
Vapor fraction	1	1	1	0.94	0	0	1	0	1	0

As is clear from the results of Tables 1 and 2, the gas fraction during compression of the gas phase was maintained at 1 in Example 1, thus making it possible to stably lead to the subsequent distillation step. In Comparative Example 1, however, the gas phase liquefied at the first stage of compression of the gas phase, and the compressor did not function, making it impossible to stably lead to the subsequent distillation step.

511, S31: Inlet of gas liquid separation device
S12, S32: Inlet of compressor
S13, S33: Outlet of compression first stage
S14: Outlet of heater
S15, S34: Outlet of compressor
S16, S35: Inlet of pump
S17, S36: Outlet of pump
S18, S37: Top of distillation column A
S19, S38: Bottom of distillation column A
S20, S39: Top of distillation column B
S21, S40: Bottom of distillation column B

Claims

A method for producing at least one fluorine-containing halogenated hydrocarbon selected from 1,1,1,2,2-pentafluoropropane (HFC-245cb), 1,1,1,3,3-pentafluoropropane (HFC-245fa), E,Z-1,3,3,3-tetrafluoropropene (E,Z-HFO-1234ze), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf) and 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), comprising
- a step of reacting a chlorine-containing compound and HF in a vapor phase, and

- a step of separating a reaction product containing HF, HCl and organic matter containing the fluorine-containing halogenated hydrocarbon into multiple components, comprising the steps of
(1) separating the reaction product into a gas phase and a liquid phase,

(2) increasing the pressure of the liquid phase and supplying the liquid phase into a distillation column A,

(3) compressing the gas phase in series in two or more stages using a compressor and heating it by a heater to maintain a fraction of compressed gas of 1 at each stage, and supplying the gas phase into distillation column A, and

(4) separating a first stream containing the HCl from the top of distillation column A, and separating a second stream containing the organic matter and the HF from the bottom of distillation column A.
The method of claim 1, wherein the chlorine-containing compound is at least one chlorine-containing alkane or alkene.
The method of claim 1, wherein the chlorine-containing compound is at least one of 1,1,1,2,3-pentachloropropane (HCC-240db), 1,1,2,2,3-pentachloropropane (HCC-240aa), 1,1,2,3-tetrachloropropene (HCO-1230xa), 2,3,3,3-tetrachloropropene (HCO-1230xf), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), 2,3-dichloro-3,3-difluoropropene (HCFO-1232xf), 1,2,3-trichloro-1,1-difluoropropane (HCFC-242dc), 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), 2,3-dichloro-1,1,1-trifluoropropane (HCFC-243db), 3,3-dichloro-1,1,1-trifluoropropane (HCFC-243fa), 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), and 3-chloro-1,1,1,3-tetrafluoropropane (HCFC-244fa).
The method of claim 1, wherein the fluorine-containing halogenated hydrocarbon comprises HFO-1234yf, and the chlorine-containing compound is at least one of HCC-240db, HCC-240aa, HCO-1230xa, HCO-1230xf, HCFO-1233xf, HCFO-1232xf, HCFC-242dc, HCFO-1233zd and HCFC-243db.
The method of claim 4, wherein the chlorine-containing compound comprises HCFO-1233xf.
The method of any of claims 1-5, wherein the molar ratio of HF to the chlorine-containing compound at the beginning of the reaction of the chlorine-containing compound and HF in the vapor phase is ≥ 10.
The method of any of claims 1-6, wherein when the gas phase is compressed in series in two or more stages in step (3), the compression rate at each stage is ≥ 2 times.
The method of any of claims 1-7, further comprising a step of supplying the second stream into a distillation column B and separating the second stream into a third stream containing the fluorine-containing halogenated hydrocarbon and a fourth stream containing the HF and organic matter other than the fluorine-containing halogenated hydrocarbon by distillation.